Great Britain Patent Application No. 2,299,327 discloses a belt transport system in a sheet folding apparatus. A plurality of transport belts each form a loop around a number of guide members and a cylinder. Tensioning devices are provided to adjust the tension in the belts. A single tensioning member, via a cantilever mechanism, adjusts the tension in the plurality of belts. To facilitate removal and replacement of worn transport belts, one end of each guide member and the corresponding end of the cylinder are disengageable from their mountings. The disengagement may be by axial separation of mountings away from the associated ends of the guide members and cylinder. The tensioning device is deactivated prior to belt removal to create slack in the belt thus facilitating removal. One of the guide members may take the form of coaxial pulleys for the individual belts. The cylinder to which the tapes are assigned may be, for example, a folding cylinder of a folding apparatus.
Known embodiments and implementations of tensioning devices include individual arms assigned to a common pivot axis. The common pivot arrangement suffers from the disadvantage that tensions from one tape to another can vary due to the lack of the individual tension control of tapes employing a common pivot axis. Tension adjustment in individual tapes is not provided by this arrangement. On the other hand, individual spring loaded tensioner arms are conceivable, but are difficult to design with close spacing to each other. Furthermore, the known implementations do not provide adequate space for easy tape changes.
A pivoting tensioner arrangement, as known in the prior art, requires relatively large amounts of space to take up increased tape slack. This is especially pertinent for two position tape path systems. That is, a tape system may include a first path around its respective rollers wherein one of the rollers assumes a first position that corresponds to an operating position. The roller may be adjustable to a second position which may correspond, for example, to a maintenance position or a second operating position. The roller's second position may create a shorter tape path than the roller's first position, in which case it is advantageous for the tape tensioners to take up the excess tape. A pivoting tensioner requires a radius through which the tensioner moves to take up the slack. It would be desirable to provide tensioning rollers that may take up the excess tape by substantially linear displacement, thus not requiring as much space as a pivoting system that includes radial lever arms and a radial motion. Further, due to wear of the tapes and dependent upon the slack requirement between the respective two positions, a correct tape tension is more difficult to maintain and adjust with a pivoting tape tensioning system compared with a tape tensioning system according to the present invention.